Fix corner case bug in numeric to_char().

Trailing-zero stripping applied by the FM specifier could strip zeroes
to the left of the decimal point, for a format with no digit positions
after the decimal point (such as "FM999.").

Reported and diagnosed by Marti Raudsepp, though I didn't use his patch.

diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 7efd988362889346af86c642f6ee660a4ae1b3d2..a7000250b0363165bee5697ad72036aad28b830e 100644 (file)
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -3908,6 +3908,9 @@ NUM_prepare_locale(NUMProc *Np)
 /* ----------
  * Return pointer of last relevant number after decimal point
  *     12.0500 --> last relevant is '5'
+ *     12.0000 --> last relevant is '.'
+ * If there is no decimal point, return NULL (which will result in same
+ * behavior as if FM hadn't been specified).
  * ----------
  */
 static char *
@@ -3921,7 +3924,8 @@ get_last_relevant_decnum(char *num)
 #endif
 
        if (!p)
-               p = num;
+               return NULL;
+
        result = p;
 
        while (*(++p))
@@ -4458,13 +4462,22 @@ NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, char *number,
        {
                Np->num_pre = plen;
 
-               if (IS_FILLMODE(Np->Num))
+               if (IS_FILLMODE(Np->Num) && IS_DECIMAL(Np->Num))
                {
-                       if (IS_DECIMAL(Np->Num))
-                               Np->last_relevant = get_last_relevant_decnum(
-                                                                                                                        Np->number +
-                                                                        ((Np->Num->zero_end - Np->num_pre > 0) ?
-                                                                         Np->Num->zero_end - Np->num_pre : 0));
+                       Np->last_relevant = get_last_relevant_decnum(Np->number);
+
+                       /*
+                        * If any '0' specifiers are present, make sure we don't strip
+                        * those digits.
+                        */
+                       if (Np->last_relevant && Np->Num->zero_end > Np->num_pre)
+                       {
+                               char   *last_zero;
+
+                               last_zero = Np->number + (Np->Num->zero_end - Np->num_pre);
+                               if (Np->last_relevant < last_zero)
+                                       Np->last_relevant = last_zero;
+                       }
                }
 
                if (Np->sign_wrote == FALSE && Np->num_pre == 0)

diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index d9927b79151f7ce550e8eabb5a110fe0844eac88..71c520e5e7a03edd55578e76de01b32aa93715ff 100644 (file)
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -1154,6 +1154,24 @@ SELECT '' AS to_char_23, to_char(val, '9.999EEEE')                               FROM num_data;
             | -2.493e+07
 (10 rows)
 
+SELECT '' AS to_char_24, to_char('100'::numeric, 'FM999.9');
+ to_char_24 | to_char 
+------------+---------
+            | 100.
+(1 row)
+
+SELECT '' AS to_char_25, to_char('100'::numeric, 'FM999.');
+ to_char_25 | to_char 
+------------+---------
+            | 100
+(1 row)
+
+SELECT '' AS to_char_26, to_char('100'::numeric, 'FM999');
+ to_char_26 | to_char 
+------------+---------
+            | 100
+(1 row)
+
 -- TO_NUMBER()
 --
 SELECT '' AS to_number_1,  to_number('-34,338,492', '99G999G999');

diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index a1435ec85ee0e7b59f24cabc1e5f9e9a435e0383..b2dc46fae28700f5dd039d46bb025f2f12333c45 100644 (file)
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -764,6 +764,10 @@ SELECT '' AS to_char_21, to_char(val, '999999SG9999999999')                        FROM num_data;
 SELECT '' AS to_char_22, to_char(val, 'FM9999999999999999.999999999999999')    FROM num_data;
 SELECT '' AS to_char_23, to_char(val, '9.999EEEE')                             FROM num_data;
 
+SELECT '' AS to_char_24, to_char('100'::numeric, 'FM999.9');
+SELECT '' AS to_char_25, to_char('100'::numeric, 'FM999.');
+SELECT '' AS to_char_26, to_char('100'::numeric, 'FM999');
+
 -- TO_NUMBER()
 --
 SELECT '' AS to_number_1,  to_number('-34,338,492', '99G999G999');